Valve tappet



Sept 7, 1943- c. L. BRACKETT 2,328,706

VALVE TAPPET Filed May 25. 1959 ative axial movement,

Patented Sept. 7, 1943 OFFICE cial-e L. Bracken, Detroit;

Application May 25, iseaseri 4 (nuns. loi, 157i This invention lrelates to the art Vof Yscrew threaded elements, and particularly to engaged complemental screw threaded elementswhichare tease locked in positions oraejustment; sitemmanner oi locking such' y'assenribly is by r the empioyment oi a jam nut, also termed a tension nut, in threaded engagement with onelnemi ber and bearing against an abutment on the other whereby lto" Vsetup an axial tension inthe assembly; by which the threadsnareplaced under tension' and thus bindf the 'respective Vmembers against relative rotation.Y =The degree o f tension is determinable by measurement oi'thetoreue required to effectv rotation or one of the elements, Thus; within is Vtin-:cretically Vpossible to Vestablish any desired tension." i

It is. however, a npractical 'impossibility with the means of prior artpraetice to maintain an established tension over extended periods of time and i1 This is especially trueV wtih assemblis'siich as valve lliter'tappet screwsand nuts, andthe like,` which are subjected'to such constant shoeii and vibration inservice that the `tension nuts soon become loosened; thetension beine there- Y upon immediately` destroyed; Furthermore, in such assemblies the vrengagedelernentsvrn'ay not bei moved axially relative to each other through any appreciableV extent withoutfailectingl the position of the nutfandlthusffcansing a variation from the establishedtension. s object rilV thisi'nventlon is'to fprovide means forY locking andfmaintaining engaged `screw threaded elements at an established thread tension unaffected by duration orconditionsiof service- LV i A 1 i Y Y Y Y Another objectis toprovide in an assembly of engaged Screwgthreaded elements carisalblcformel-fV means for setting up a predetfrmlneddeeiredgthread tension therebetween and maintaining the same irrespective of the frequency and extent of axial movement of either member relative to the other.

Still another object is to provide a novel tappet screw assembly having means operative independently of either the screw or its lifter socket to create and maintain throughout the life of the assembly a desired degree of tension on the engaged threads thereof.

A further object assembly a novel means der a desired screw thread tension, permits axial adjustment oi' the screw in t er socket without in any way disturbing tablished tension.

the tensile limits o! the threads; it 1 Y Other objects will be readily apparent to those skilled'linthe art.

er :Although'not restricted thereto, the invention islparticularlyuseinl as appliedV in valve lifter assemblies and the like. For puroeesr iilustration auch an assembly is shown in theacdempanylng drawing and described hereinpbut itis to be understood that within the scope of the invention as claimed all disclosed details'oi structure may be varied as desired.

f In'the drawing:

Figure 1 is an elevation of a valve lifter tappet screwV with a tension nut as initially positioned thereon.

Figure 2 is an axial section, partly in elevation, of an assembly before tightening the tension nut.

l Figurei lean elevation, partly in axial section, on thefcompleted assembly, showing thenut under stress "as assembled. il'igure 4 is an enlarged axial section through the'fupper portion of the complete assembly shiivminliguref.- f i Y :.li'igureY 5 isa section similar toiFigure ibut illustrating the use oi a'dfferent type'ot nut,v i L YIn'structurai detail the assembly comprises a pain ofccomplementally threaded members 5 and Shine Vconnectedl engagement, with a threaded stem-eli cnaV the male Vmember 5 received in `a. threaded "axial socket B ln the female member 6. A trrisionenutV 9e is threaded ontothe stem 1 and isairialiy adjustable thereon to bear against an abutmenton a female member, which abutment is conveniently the adjacent end of the member 6. When the nut 9 is rotated on the stem 1 and forced against the abutment on the female memberrthe two members will be forced axially in oppositedirectlons outwardly with respect to the assembly. creating an axial tension on the engssedrfscrew Ythreads in the known manner of Y Suela nuts. Y' f f- In the disclosed embodiment the male member 5 is a valve tappet screw and the female member E is its lifter; both are of conventional construction and operation in service. The nut 9 shown in Figures l-4 is preferably, but not necessarily, of the form shown in United States Patent No. 1,734,445 of Nov. 5, 1929; with its bottom face having a concave area ID surrounding its bore and having a flat peripheral zone il of relatively short radial extent which bears against the flat shoulder formed by the upper end of the lifter socket. A series of radial slots, one of which is shown as at l2 in Figure 3, extend through its upper half portion from the hexagonal sides to its bore. The top and bottom peripheral edges of the nut are preferably chamfered, as is also the end of the lifter.

In effecting the assembly the nut 9 is applied to the stem of the tappet screw at approximately the position it will occupy when the tappet is adjusted; this step is illustrated in Figure l. The stem of the screw is next threaded into the bore of the lifter socket 6, and by the ald of proper tools such as wrenches I3, I4 and I5 applied, respectively, tothe lifter. them-it and the screw, the mi is lightmed down lg'alst tlm adjacent end of the lifter against which it bears. This step is illustrated in Figure 2.

Figure 4 makes clear that when the nut ls tightened the tappet screw stem l will be ozfd axially outwardly with respect to the llftercket so that the upper inclined faces of the threads on the tappet screw will bear tightly against he inclined lower faces of the lifter socket threads, creating an axial tension in the threads which increases corrpondingiy with an imm in the pressure at which the nut is forced against end of the lifter socket due to the resilience of the nut. At the same time, the flat face pnrtim H of the mit provides a mlm-um onrwhlch the slottui upper portion of the mrt mds im mok mdinlly inward as the nut is tightened. Bris action causes the upper part of the nut te bear tightiy against the tappet `screw siem with the nut threads being faim seated in the stem threads, as shown in Figure 4, and sets up a radial tension in addition to the axial tension.

The degree of tension can he measured by means of a conventional torque wrench which may be the wrench 1S applied to the head of the tappe: screw, and in this manner the nut may be operated to estabmh any deslrcd'tension, as the tension is proporiiomlo torque. The torque in valve tappet screw varies usually between 82 to im inch pounds, as upprcximate limits established by good engineeringV practice, and by the practiceof www it is possible tc keep the torque definitely within any predetermined given range.

When the desired tension has been established the nut is permanently fixed against rotation. Preferably this anchoring of the nut is accomplished by SDOt welding, as at I6, over the adjacent chamered areas of the nut bottom and the end cf the lifter. By this means the mit is welded to the lifter and becomes, in eiect, an lntegrai part thereof. It is rendered incapable oit movement with respect either to the lifter or to the tappet screw.

The final pxial adjustment of the tappet screw 5 is then made, and it is an innmrrtantV feature of this invention that the screw may be moved axially in the lifter socket to any desired extent without in any way affecting the thread tension previously established by adjustment of the ten.

sion nut and its permanent fixation with respect to the lifter.

The embodiment shown in Figure 5 is identical with that of Figures l to 4 except that the nut 9' ls a plain check nut with a flat bottom face. The elements which correspond to those of the preceding views are designated by the same reference characters.

It will be apparent that due to the impossibility of relaverrmmment begween the mit and lifter, ater tlie mit has been'djste and permanently fixed thereon, the thread tension or torque, once Vestablished at the desired degree, will remain at that same degree throughout the life of the assembly and will be unaffected by shocks and vibrations incident to service.

I claim:V

1. A valve lifter tappet screw assembly comprising a lifter, a tappet screw in threaded adjustable engagement therewith, a tension nut on the screw and tensioned against the lifter to festablish a desired thread tension beimrcenV the screw and lifter, and means zcedly securing said nut to said lifter while the mit is uncbr tlhe Ies tablished tension to maintain such tension and at the same time permit adjustment of .said tane pet screw. Y

2. A valve lifter tappetscrew assemwy come prising a lifteipa 21439643 Screw in 'threaded `ad" .instable engagement therewith, a tension nut on the screw externally of lifter and tensiones! against theflifter to establish a desired thread tension between thescrew'and lifter, aand said nut being welded in place on the lifter'while under tension and in-the position at which the desired thread tension is established'to maintain such tension and at the same time permit andd justment of slid-tamtscrew. y Y

3. A valve lifter screw assembly comprising s. lifter. a tappessuw in threaded adjustable engggment therewith tension'mg means cooperatively associated. with beth and being initially rotatae relative te both to establish a desired thread tmsion between the two, and said means" being permeaentlyami dxedly connected to one inthe position at which the desired tension is established. s

4. A valve lifter tappet'screw assemiy'compxising a, lifter, etappe# screw in threaded adi instable. engagementY therewith, tensioning means initially rotatahieon the screw externaliy of the lifter into bearing engagement against the lifter to impart an axial thread tension between said sew'lifter, and means Isernia neatly and rigidly'A connecting said tensioning means to said lifter in the position of esta lished thread tension to maintain? such tensic vwhile permittingy adjustment of said tappet ser w. 

